The technical scope of the invention is that of translational braking devices for a projectile during its trajectory.
Such devices are notably known in the field of artillery.
Patent EP138942thus describes an artillery projectile that incorporates a device to brake the nose cone whose deployment is controlled during the trajectory.
Such an arrangement allows firing accuracy of artillery fires to be increased whilst taking into account dispersions due to the variations in initial velocity of the projectile. Indeed, it is thus possible to lay the weapon so as to fire beyond the target aimed at, a fire control measures the real velocity of the projectile at the muzzle of the weapon and a braking command is thereafter transmitted to the projectile so as to reduce its range and thus bring it to the desired point of impact.
The braking device described by this patent comprises, either radially mobile fingers, or a plane frontal surface. The surface area of these braking means with respect to the section of the projectile is too small for their braking capacity to be sufficient.
Patent WO98/01719 describes another braking device for a projectile. This device comprises four airbrake plates stacked one on top of the other and radially mobile with respect to the projectile.
The braking area is thus substantially increased (it constitutes approximately double the section of the projectile) and is of a reduced bulk inside the projectile body.
However, this device has drawbacks.
The shapes of the plates are complicated to machine, they also incorporate numerous indents that reduce their mechanical strength, notably in their fully deployed position where the stresses are at their worst.
Moreover, the plates are unlocked by means of two gas generators that displace two retention pins, each pin immobilizing two plates. Such a structure is likely to cause dissymmetries or sticking when the plates are deploying that risk modifying the trajectory of the projectile in a non-reproducible manner.